Julian has a total of 33 of green and purple pens.
13 of the green pens and half of the purple pens are new. How many of his purple pens are new if he has a total of 13 new pens?
| |
Green pens |
Purple pens |
Total |
| Total |
3 u |
2 p |
33 |
| New |
1 u |
1 p |
13 |
| Old |
2 u |
1 p |
20 |
Number of old pens
= 33 - 13
= 20
1 u + 1 p = 13 --- (1)
2 u + 1 p = 20 --- (2)
(2) - (1)
(2 u + 1 p) - (1 u + 1 p) = 20 - 13
2 u - 1 u = 7
1 u = 7
1 u = 7 ÷ 1 = 7
Number of new purple pens
= 13 - 1 u
= 13 - 7
= 6
Answer(s): 6
